Stent with improved anti-migration properties

ABSTRACT

An esophageal stent configured to span a stricture may include a tubular body configured to shift between a delivery configuration and a deployed configuration, the tubular body having a first end and a second end. In the deployed configuration: the tubular body defines a first flange portion, a second flange portion, and a saddle portion extending from the first flange portion to the second flange portion; the tubular body further defining an overall longitudinal length extending from the first end to the second end; the first flange portion has a first outer radial extent, and the second flange portion has a second outer radial extent; the first outer radial extent and the second outer radial extent are greater than an outer radial extent of the saddle portion; and a longitudinal length of the saddle portion is at least 50% of the overall longitudinal length of the tubular body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. § 119 ofU.S. Provisional Application No. 62/936,922, filed Nov. 18, 2019, theentire disclosure of which is hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure pertains to medical devices, and methods formanufacturing and/or using medical devices. More particularly, thepresent disclosure pertains to an improved design for an endoprosthesisor stent.

BACKGROUND

Some conditions may cause body lumens (e.g., the esophagus, the bileduct, the trachea, the gastrointestinal tract, the vascular system,etc.) becoming restricted, such as by a stricture formation. As aresult, it may be necessary to open the body lumen to permit normalfunction. Some body lumens may be treated with a self-expanding stent.However, some body lumens are also prone to unintended and/or undesiredmovement or migration of the stent. Some stents have been designed witha flare on one or both ends with an intent to improve anchoring withinthe body lumen. However, the flared end(s) can sometimes haveundesirable consequences, including perforation of the body lumen and/orstenosis formation. There is an ongoing need to provide alternativeendoprostheses or stents as well as alternative methods formanufacturing and using endoprostheses or stents.

SUMMARY

In a first aspect, a stent, such as an esophageal stent, configured tospan a stricture may comprise a tubular body configured to shift betweena delivery configuration and a deployed configuration, the tubular bodyhaving a first end and a second end. In the deployed configuration, thetubular body may define a first flange portion proximate the first end,a second flange portion proximate the second end, and a saddle portionextending from the first flange portion to the second flange portion. Inthe deployed configuration, the tubular body may further define anoverall longitudinal length extending from the first end to the secondend. In the deployed configuration, the saddle portion may have an outerradial extent, the first flange portion may have a first outer radialextent, and the second flange portion may have a second outer radialextent. In the deployed configuration, the first outer radial extent maybe greater than the outer radial extent of the saddle portion. In thedeployed configuration, the second outer radial extent may be greaterthan the outer radial extent of the saddle portion. In the deployedconfiguration, a longitudinal length of the saddle portion may be atleast 50% of the overall longitudinal length of the tubular body.

In addition or alternatively, in the deployed configuration, the firstflange portion may comprise a first flange proximate the first end and asecond flange longitudinally spaced apart from the first flange towardthe second end.

In addition or alternatively, in the deployed configuration, the secondflange may be spaced apart from the first flange about 5 mm to about 10mm.

In addition or alternatively, in the deployed configuration, the secondflange portion may comprise a third flange proximate the second end anda fourth flange longitudinally spaced apart from the third flange towardthe first end.

In addition or alternatively, in the deployed configuration, the fourthflange may be spaced apart from the third flange about 5 mm to about 10mm.

In addition or alternatively, in the deployed configuration, the firstflange portion may be configured to resist a first radial inward force,the second flange portion may be configured to resist a second radialinward force, and the saddle portion may be configured to resist a thirdradial inward force less than the first radial inward force and thesecond radial inward force.

In addition or alternatively, in the deployed configuration, the firstradial inward force may be within 10% of the second radial inward force.

In addition or alternatively, in the deployed configuration, the thirdradial inward force may be less than 75% of the first radial inwardforce or the second radial inward force.

In addition or alternatively, in the deployed configuration, thelongitudinal length of the saddle portion may be at least 75% of theoverall length of the tubular body.

In addition or alternatively, at least a portion of the tubular body mayinclude a cover member.

In addition or alternatively, an esophageal stent configured to span astricture may comprise a tubular body configured to shift between adelivery configuration and a deployed configuration, the tubular bodyhaving a first end and a second end. In the deployed configuration, thetubular body may define a first flange portion proximate the first end,a second flange portion proximate the second end, and a saddle portionextending from the first flange portion to the second flange portion. Inthe deployed configuration, the tubular body may further define anoverall longitudinal length extending from the first end to the secondend. In the deployed configuration, the saddle portion may have an outerradial extent, the first flange portion may have a first outer radialextent, and the second flange portion may have a second outer radialextent. In the deployed configuration, the first outer radial extent maybe greater than the outer radial extent of the saddle portion. In thedeployed configuration, the second outer radial extent may be greaterthan the outer radial extent of the saddle portion. In the deployedconfiguration, the saddle portion may include a first radially inwardtaper extending from the first flange portion toward the second flangeportion.

In addition or alternatively, in the deployed configuration, the saddleportion may include a second radially inward taper extending from thesecond flange portion toward the first flange portion.

In addition or alternatively, in the deployed configuration, the firstflange portion may comprise a first flange proximate the first end and asecond flange longitudinally spaced apart from the first flange towardthe second end.

In addition or alternatively, in the deployed configuration, the secondflange may be spaced apart from the first flange about 5 mm to about 10mm.

In addition or alternatively, in the deployed configuration, the secondflange portion may comprise a third flange proximate the second end anda fourth flange longitudinally spaced apart from the third flange towardthe first end.

In addition or alternatively, in the deployed configuration, the fourthflange may be spaced apart from the third flange about 5 mm to about 10mm.

In addition or alternatively, in the deployed configuration, the secondouter radial extent may be within 10% of the first outer radial extent.

In addition or alternatively, in the deployed configuration, the secondouter radial extent may be within 5% of the first outer radial extent.

In addition or alternatively, at least a portion of the tubular body mayinclude a cover member.

In addition or alternatively, a method of treating a stricture in a bodylumen may comprise positioning a stent within the body lumen in adelivery configuration, wherein the stent may be positioned with asaddle portion of the stent spanning the stricture, a first flangeportion proximal of the stricture, and a second flange portion distal ofthe stricture. The method may further comprise shifting the stent fromthe delivery configuration to a deployed configuration. In the deployedconfiguration, the first flange portion may have a first outer radialextent greater than an outer radial extent of the saddle portion. In thedeployed configuration, the second flange portion may have a secondouter radial extent greater than the outer radial extent of the saddleportion. In the deployed configuration, a first flange of the firstflange portion and a second flange of the first flange portionlongitudinally spaced apart from the first flange may capture a firstportion of a wall of the body lumen therebetween to anchor the stentadjacent the stricture. In the deployed configuration, a third flange ofthe second flange portion and a fourth flange of the second flangeportion longitudinally spaced apart from the third flange may capture asecond portion of the wall of the body lumen therebetween to anchor thestent adjacent the stricture.

The above summary of some embodiments, aspects, and/or examples is notintended to describe each disclosed embodiment or every implementationof the present disclosure. The Figures, and Detailed Description, whichfollow, more particularly exemplify these embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may be more completely understood in consideration of thefollowing detailed description in connection with the accompanyingdrawings, in which:

FIG. 1 illustrates aspects of an example stent;

FIG. 2 illustrates aspects of an example stent;

FIG. 3 illustrates aspects of an example stent; and

FIGS. 4 and 5 illustrate aspects of a method of treating a stricture ina body lumen.

While aspects of the disclosure are amenable to various modificationsand alternative forms, specifics thereof have been shown by way ofexample in the drawings and will be described in detail. It should beunderstood, however, that the intention is not to limit aspects of thedisclosure to the particular embodiments described. On the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the disclosure.

DETAILED DESCRIPTION

The following description should be read with reference to the drawings,which are not necessarily to scale, wherein like reference numeralsindicate like elements throughout the several views. The detaileddescription and drawings are intended to illustrate but not limit theclaimed invention. Those skilled in the art will recognize that thevarious elements described and/or shown may be arranged in variouscombinations and configurations without departing from the scope of thedisclosure. The detailed description and drawings illustrate exampleembodiments of the claimed invention.

For the following defined terms, these definitions shall be applied,unless a different definition is given in the claims or elsewhere inthis specification.

All numeric values are herein assumed to be modified by the term“about,” whether or not explicitly indicated. The term “about”, in thecontext of numeric values, generally refers to a range of numbers thatone of skill in the art would consider equivalent to the recited value(e.g., having the same function or result). In many instances, the term“about” may include numbers that are rounded to the nearest significantfigure. Other uses of the term “about” (e.g., in a context other thannumeric values) may be assumed to have their ordinary and customarydefinition(s), as understood from and consistent with the context of thespecification, unless otherwise specified.

The recitation of numerical ranges by endpoints includes all numberswithin that range, including the endpoints (e.g., 1 to 5 includes 1,1.5, 2, 2.75, 3, 3.80, 4, and 5).

Although some suitable dimensions, ranges, and/or values pertaining tovarious components, features and/or specifications are disclosed, one ofskill in the art, incited by the present disclosure, would understanddesired dimensions, ranges, and/or values may deviate from thoseexpressly disclosed.

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. As used in this specification and theappended claims, the term “or” is generally employed in its senseincluding “and/or” unless the content clearly dictates otherwise. It isto be noted that in order to facilitate understanding, certain featuresof the disclosure may be described in the singular, even though thosefeatures may be plural or recurring within the disclosed embodiment(s).Each instance of the features may include and/or be encompassed by thesingular disclosure(s), unless expressly stated to the contrary. Forsimplicity and clarity purposes, not all elements of the disclosedinvention are necessarily shown in each figure or discussed in detailbelow. However, it will be understood that the following discussion mayapply equally to any and/or all of the components for which there aremore than one, unless explicitly stated to the contrary. Additionally,not all instances of some elements or features may be shown in eachfigure for clarity.

Relative terms such as “proximal”, “distal”, “advance”, “retract”,variants thereof, and the like, may be generally considered with respectto the positioning, direction, and/or operation of various elementsrelative to a user/operator/manipulator of the device, wherein“proximal” and “retract” indicate or refer to closer to or toward theuser and “distal” and “advance” indicate or refer to farther from oraway from the user. In some instances, the terms “proximal” and “distal”may be arbitrarily assigned in an effort to facilitate understanding ofthe disclosure, and such instances will be readily apparent to theskilled artisan. Other relative terms, such as “upstream”, “downstream”,“inflow”, and “outflow” refer to a direction of fluid flow within alumen, such as a body lumen, a blood vessel, or within a device. Stillother relative terms, such as “axial”, “circumferential”,“longitudinal”, “lateral”, “radial”, etc. and/or variants thereofgenerally refer to direction and/or orientation relative to a centrallongitudinal axis of the disclosed structure or device.

The term “extent” may be understood to mean a greatest measurement of astated or identified dimension, unless the extent or dimension inquestion is preceded by or identified as a “minimum”, which may beunderstood to mean a smallest measurement of the stated or identifieddimension. For example, “outer extent” may be understood to mean anouter dimension, “radial extent” may be understood to mean a radialdimension, “longitudinal extent” may be understood to mean alongitudinal dimension, etc. Each instance of an “extent” may bedifferent (e.g., axial, longitudinal, lateral, radial, circumferential,etc.) and will be apparent to the skilled person from the context of theindividual usage. Generally, an “extent” may be considered a greatestpossible dimension measured according to the intended usage, while a“minimum extent” may be considered a smallest possible dimensionmeasured according to the intended usage. In some instances, an “extent”may generally be measured orthogonally within a plane and/orcross-section, but may be, as will be apparent from the particularcontext, measured differently—such as, but not limited to, angularly,radially, circumferentially (e.g., along an arc), etc.

The terms “monolithic” and “unitary” shall generally refer to an elementor elements made from or consisting of a single structure or baseunit/element. A monolithic and/or unitary element shall excludestructure and/or features made by assembling or otherwise joiningmultiple discrete structures or elements together.

It is noted that references in the specification to “an embodiment”,“some embodiments”, “other embodiments”, etc., indicate that theembodiment(s) described may include a particular feature, structure, orcharacteristic, but every embodiment may not necessarily include theparticular feature, structure, or characteristic. Moreover, such phrasesare not necessarily referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with an embodiment, it would be within the knowledge of oneskilled in the art to implement the particular feature, structure, orcharacteristic in connection with other embodiments, whether or notexplicitly described, unless clearly stated to the contrary. That is,the various individual elements described below, even if not explicitlyshown in a particular combination, are nevertheless contemplated asbeing combinable or arrangeable with each other to form other additionalembodiments or to complement and/or enrich the described embodiment(s),as would be understood by one of ordinary skill in the art.

For the purpose of clarity, certain identifying numerical nomenclature(e.g., first, second, third, fourth, etc.) may be used throughout thedescription and/or claims to name and/or differentiate between variousdescribed and/or claimed features. It is to be understood that thenumerical nomenclature is not intended to be limiting and is exemplaryonly. In some embodiments, alterations of and deviations from previouslyused numerical nomenclature may be made in the interest of brevity andclarity. That is, a feature identified as a “first” element may later bereferred to as a “second” element, a “third” element, etc. or may beomitted entirely, and/or a different feature may be referred to as the“first” element. The meaning and/or designation in each instance will beapparent to the skilled practitioner.

The figures illustrate selected components and/or arrangements of anendoprosthesis or stent. It should be noted that in any given figure,some features of the endoprosthesis or stent may not be shown, or may beshown schematically, for simplicity. Additional details regarding someof the components of the endoprosthesis or stent may be illustrated inother figures in greater detail. It is to be noted that in order tofacilitate understanding, certain features of the disclosure may bedescribed in the singular, even though those features may be plural orrecurring within the disclosed embodiment(s). Each instance of thefeatures may include and/or be encompassed by the singulardisclosure(s), unless expressly stated to the contrary. For example, areference to “the flange”, “the end”, “the filament”, or other featuresmay be equally referred to all instances and quantities beyond one ofsaid feature. As such, it will be understood that the followingdiscussion may apply equally to any and/or all of the components forwhich there are more than one within the endoprosthesis or stent, unlessexplicitly stated to the contrary. Additionally, not all instances ofsome elements or features may be shown in each figure for clarity.

FIG. 1 illustrates an example stent (which term may be usedinterchangeably with the term “endoprosthesis”) comprising a tubularbody 100 configured to shift between a delivery configuration (e.g.,FIG. 4 ) and a deployed configuration, the tubular body 100 having afirst end 102 and a second end 104. In some embodiments, the deliveryconfiguration may be axially elongated and/or radially collapsed orcompressed compared to the deployed configuration. The deployedconfiguration may be axially shortened and/or radially expanded comparedto the delivery configuration.

In some embodiments, the tubular body 100 may comprise an expandableframework. In at least some embodiments, the tubular body 100 and/or theexpandable framework may be self-expandable. For example, the tubularbody 100 and/or the expandable framework may be formed from a shapememory material. In some embodiments, the tubular body 100 and/or theexpandable framework may be mechanically expandable. For example, thetubular body 100 and/or the expandable framework may be expandable usingan inflatable balloon, using an actuation member, or other suitablemeans. During delivery to a treatment site, the tubular body 100 and/orthe expandable framework may be disposed within a lumen of a deliverysheath in the delivery configuration. Upon removal from the lumen of thedelivery sheath, the tubular body 100 and/or the expandable frameworkmay be shifted to the deployed configuration.

In some embodiments, in the deployed configuration, the tubular body 100and/or the expandable framework may define a first flange portion 110proximate the first end 102, a second flange portion 120 proximate thesecond end 104, and a saddle portion 130 extending from the first flangeportion 110 to the second flange portion 120. The saddle portion 130 maybe a cylindrical portion having a constant outer diameter along itsentire length, for example. The tubular body 100 and/or the expandableframework may define an overall longitudinal length 108 extending fromthe first end 102 to the second end 104. In some embodiments, alongitudinal length 138 of the saddle portion 130 may be at least 50% ofthe overall longitudinal length 108 of the tubular body 100. In someembodiments, the longitudinal length 138 of the saddle portion 130 maybe at least 75% of the overall longitudinal length 108 of the tubularbody 100. The tubular body 100 and/or the expandable framework maydefine a longitudinally oriented lumen extending therethrough from thefirst end 102 to the second end 104. In at least some embodiments, thefirst flange portion 110 and/or the second flange portion 120 may becoaxial with the saddle portion 130. In at least some embodiments, thefirst flange portion 110 and the second flange portion 120 may bemonolithically formed with the saddle portion 130 as a single unitarystructure (e.g., the plurality of interwoven filaments forming thesaddle portion 130 extend throughout the first flange portion 110 toform the first flange portion 110 and/or extend throughout the secondflange portion 120 to form the second flange portion 120). In someembodiments, at least a portion of the tubular body 100 and/or theexpandable framework extends proximal of the first flange portion 110.In some embodiments, at least a portion of the tubular body 100 and/orthe expandable framework extends distal of the second flange portion120.

In some embodiments, in the deployed configuration, the saddle portion130 may have an outer radial extent 132, the first flange portion 110may have a first outer radial extent 112, and the second flange portion120 may have a second outer radial extent 122. In some embodiments, thefirst outer radial extent 112 may be greater than the outer radialextent 132 of the saddle portion 130. In some embodiments, the secondouter radial extent 122 may be greater than the outer radial extent 132of the saddle portion 130. In some embodiments, the second outer radialextent 122 may be within about 25% of the first outer radial extent 112.In some embodiments, the second outer radial extent 122 may be withinabout 10% of the first outer radial extent 112. In some embodiments, thesecond outer radial extent 122 may be within about 5% of the first outerradial extent 112. In some embodiments, the second outer radial extent122 may be equal to the first outer radial extent 112. In someembodiments, the outer radial extent 132 of the saddle portion 130 maybe about 10 mm (millimeters) to about 30 mm, about 14 mm to about 25 mm,about 16 mm to about 22 mm, or another suitable range. In someembodiments, the first outer radial extent 112 and/or the second outerradial extent 122 may be about 20 mm to about 40 mm, about 24 mm toabout 35 mm, about 26 mm to about 32 mm, or another suitable range. Insome embodiments, an outer radial extent of the tubular body 100 and/orthe expandable framework at the first end 102 may be substantially equalto an outer radial extent of the tubular body 100 and/or the expandableframework at the second end 104. Other configurations are alsocontemplated.

In some embodiments, in the deployed configuration, the first flangeportion 110 may comprise multiple spaced apart flanges, such as a firstflange 114 proximate the first end 102 and a second flange 116longitudinally spaced apart from the first flange 114 toward the secondend 104. The first flange 114 and the second flange 116 may be orientedgenerally transverse to a central longitudinal axis of the tubular body100. In some embodiments, the second flange 116 may be longitudinallyspaced apart from the first flange 114 about 2 mm to about 20 mm, about4 mm to about 15 mm, about 5 mm to about 10 mm, or another suitablerange. In some embodiments, the first flange 114 and/or the secondflange 116 may have an axial thickness of about 1 mm to about 7 mm,about 2 mm to about 6 mm, about 3 mm to about 5 mm, or another suitablerange. Other configurations are also contemplated.

In some embodiments, in the deployed configuration, the second flangeportion 120 may comprise multiple spaced apart flanges, such as a thirdflange 124 proximate the second end 104 and a fourth flange 126longitudinally spaced apart from the third flange 124 toward the firstend 102. The third flange 124 and the fourth flange 126 may be orientedgenerally transverse to the central longitudinal axis of the tubularbody 100. In some embodiments, the fourth flange 126 may belongitudinally spaced apart from the third flange 124 about 2 mm toabout 20 mm, about 4 mm to about 15 mm, about 5 mm to about 10 mm, oranother suitable range. In some embodiments, the third flange 124 and/orthe fourth flange 126 may have an axial thickness of about 1 mm to about7 mm, about 2 mm to about 6 mm, about 3 mm to about 5 mm, or anothersuitable range. Other configurations are also contemplated.

In some embodiments, in the deployed configuration, the first flangeportion 110 (and/or the first flange 114 and the second flange 116) maybe configured to resist collapsing radially inward under a first radialinward force, the second flange portion 120 (and/or the third flange 124and the fourth flange 126) may be configured to resist collapsingradially inward under a second radial inward force, and the saddleportion 130 may be configured to resist collapsing radially inward undera third radial inward force less than the first radial inward force andthe second radial inward force. In some embodiments, the first radialinward force may be within about 25% of the second radial inward force.In some embodiments, the first radial inward force may be within about10% of the second radial inward force. In some embodiments, the firstradial inward force may be within about 5% of the second radial inwardforce. In some embodiments, the third radial inward force may be lessthan about 75% of the first radial inward force and/or the second radialinward force. In some embodiments, the third radial inward force may beless than about 50% of the first radial inward force and/or the secondradial inward force. In some embodiments, the first radial inward forceand/or the second radial inward force may be about 300% to about 500%greater than the third radial inward force. Other configurations arealso contemplated.

In some embodiments, in the deployed configuration, the tubular body 100may define an outer surface that may extend, sequentially, from thefirst end: longitudinally, radially outward, curve back on itself toradially inward, longitudinally, radially outward, curve back on itselfto radially inward, longitudinally, radially outward, curve back onitself to radially inward, longitudinally, radially outward, curve backon itself to radially inward, and longitudinally, to the second end. Inother words, each flange may include first and second radially extendingwall portions longitudinally spaced apart from one another with anapical curved region spanning therebetween at the outer extent of theflange, with a first radially extending wall portion extend radiallyoutward from the central longitudinal axis to an outer extent of theflange and the second radially extending wall portion extending radiallyinward from the outer extent of the flange toward the centrallongitudinal axis. Other configurations are also contemplated.

In some embodiments, the tubular body 100 may be formed from a pluralityof filaments or wires that may be woven, braided, wound, knitted, andcombinations thereof, around a central longitudinal axis to form thetubular body 100. The tubular body 100 may include multiple filaments orwires of a metal material, such as nitinol or nitinol-containingmaterial, or other nickel-titanium alloy, for example. In someinstances, the filaments or wires may have a diameter of about 0.011inches (0.2794 mm), for example. The number and the diameters of thefilaments or wires, which may be the same or different, are notlimiting, and other numbers and other diameters of filaments or wiresmay suitably be used. Desirably, an even number of filaments or wiresmay be used, for example, from about 2 to about 50 filaments or wires,about 6 to about 40 filaments or wires, about 10 to about 36 filamentsor wires, etc.

Desirably, the filaments or wires are made from any suitable implantablebiocompatible material, including without limitation nitinol, stainlesssteel, cobalt-based alloy such as Elgiloy®, platinum, gold, titanium,tantalum, niobium, polymeric materials and combinations thereof. Usefuland nonlimiting examples of polymeric stent materials includepoly(L-lactide) (PLLA), poly(D,L-lactide) (PLA), poly(glycolide) (PGA),poly(L-lactide-co-D,L-lactide) (PLLA/PLA), poly(L-lactide-co-glycolide)(PLLA/PGA), poly(D,L-lactide-co-glycolide) (PLA/PGA),poly(glycolide-co-trimethylene carbonate) (PGA/PTMC), polydioxanone(PDS), Polycaprolactone (PCL), polyhydroxybutyrate (PHBT),poly(phosphazene) poly(D,L-lactide-co-caprolactone) PLA/PCL),poly(glycolide-co-caprolactone) (PGA/PCL), poly(phosphate ester) and thelike. Filaments or wires made from polymeric materials may also includeradiopaque materials, such as metallic-based powders, particulates orpastes which may be incorporated into the polymeric material. Forexample, the radiopaque material may be blended with the polymercomposition from which the polymeric filaments or wires are formed, andsubsequently fashioned into the tubular body 100 as described herein.Alternatively, the radiopaque material may be applied to the surface ofthe metal or polymer filaments or wires of the tubular body 100. Ineither embodiment, various radiopaque materials and their salts andderivatives may be used including, without limitation, bismuth, bariumand its salts such as barium sulphate, tantalum, tungsten, gold,platinum and titanium, to name a few. Additional useful radiopaquematerials may be found in U.S. Pat. No. 6,626,936, the contents of whichare incorporated herein by reference. Metallic complexes useful asradiopaque materials are also contemplated. The tubular body 100 may beselectively made radiopaque at desired areas along the filaments orwires or may be fully radiopaque.

In some instances, the filaments or wires may have a compositeconstruction having an inner core of tantalum, gold, platinum, tungsten,iridium or combination thereof and an outer member or layer of nitinolto provide a composite wire for improved radiopacity or visibility. Inone example, the inner core may be platinum and the outer layer may benitinol. The inner core of platinum may represent about at least 10% ofthe filaments or wires based on overall cross-sectional percentage.Moreover, nitinol that has not been treated for shape memory such as byheating, shaping and cooling the nitinol at its martensitic andaustenitic phases, is also useful as the outer layer. Further details ofsuch composite wires may be found in U.S. Patent No. 7,101,392, thecontents of which is incorporated herein by reference. The filaments orwires may be made from nitinol, or composite filaments or wires having acentral core of platinum and an outer layer of nitinol. Further, thefilling weld material, if required by welding processes such as MIG, mayalso be made from nitinol, stainless steel, cobalt-based alloy such asElgiloy, platinum, gold, titanium, tantalum, niobium, and combinationsthereof. Additional and/or other materials suitable for use in thetubular body 100 are described below.

In some embodiments, the tubular body 100 may optionally include apolymeric cover 140 disposed on at least a portion of the tubular body100 and/or the expandable framework. In some embodiments, the polymericcover 140 may be disposed on the saddle portion 130, as shown in FIG. 1for example. In some embodiments, the polymeric cover 140 mayadditionally or alternatively be disposed on the first flange portion110 and/or the second flange portion 120. In some embodiments, thepolymeric cover 140 may be disposed on the first flange portion 110, thesecond flange portion 120, and the saddle portion 130. In someembodiments, the polymeric cover 140 may be disposed on and/or along anouter surface of the tubular body 100 and/or the expandable framework.In some embodiments, the tubular body 100 and/or the expandableframework may be embedded in the polymeric cover 140. In someembodiments, the polymeric cover 140 may be disposed on and/or along aninner surface of the tubular body 100 and/or the expandable framework.In some embodiments, the polymeric cover 140 may be fixedly orreleasably secured to, bonded to, or otherwise attached to the tubularbody 100 and/or the expandable framework. In some embodiments, thepolymeric cover 140 may be impermeable to fluids, debris, medicalinstruments, etc. Some suitable but non-limiting materials for thepolymeric cover 140 are described below.

FIG. 2 illustrates an example stent (which term may be usedinterchangeably with the term “endoprosthesis”) comprising a tubularbody 200 configured to shift between a delivery configuration (e.g.,FIG. 4 ) and a deployed configuration, the tubular body 200 having afirst end 202 and a second end 204. In some embodiments, the deliveryconfiguration may be axially elongated and/or radially collapsed orcompressed compared to the deployed configuration. The deployedconfiguration may be axially shortened and/or radially expanded comparedto the delivery configuration. The tubular body 200 may be constructedand/or may function similar to the tubular body 100 described herein,except for any specific differences noted.

In some embodiments, the tubular body 200 may comprise an expandableframework. In at least some embodiments, the tubular body 200 and/or theexpandable framework may be self-expandable. For example, the tubularbody 200 and/or the expandable framework may be formed from a shapememory material. In some embodiments, the tubular body 200 and/or theexpandable framework may be mechanically expandable. For example, thetubular body 200 and/or the expandable framework may be expandable usingan inflatable balloon, using an actuation member, or other suitablemeans. During delivery to a treatment site, the tubular body 200 and/orthe expandable framework may be disposed within a lumen of a deliverysheath in the delivery configuration. Upon removal from the lumen of thedelivery sheath, the tubular body 200 and/or the expandable frameworkmay be shifted to the deployed configuration.

In some embodiments, in the deployed configuration, the tubular body 200and/or the expandable framework may define a first flange portion 210proximate the first end 202, a second flange portion 220 proximate thesecond end 204, and a saddle portion 230 extending from the first flangeportion 210 to the second flange portion 220. The tubular body 200and/or the expandable framework may define an overall longitudinallength 208 extending from the first end 202 to the second end 204. Insome embodiments, a longitudinal length 238 of the saddle portion 230may be at least 50% of the overall longitudinal length 208 of thetubular body 200. In some embodiments, the longitudinal length 238 ofthe saddle portion 230 may be at least 75% of the overall longitudinallength 208 of the tubular body 200. The tubular body 200 and/or theexpandable framework may define a longitudinally oriented lumenextending therethrough from the first end 202 to the second end 204. Inat least some embodiments, the first flange portion 210 and/or thesecond flange portion 220 may be coaxial with the saddle portion 230. Inat least some embodiments, the first flange portion 210 and the secondflange portion 220 may be monolithically formed with the saddle portion230 as a single unitary structure. In some embodiments, at least aportion of the tubular body 200 and/or the expandable framework extendsproximal of the first flange portion 210. In some embodiments, at leasta portion of the tubular body 200 and/or the expandable frameworkextends distal of the second flange portion 220.

In some embodiments, in the deployed configuration, the saddle portion230 may have an outer radial extent 232, the first flange portion 210may have a first outer radial extent 212, and the second flange portion220 may have a second outer radial extent 222. In some embodiments, thefirst outer radial extent 212 may be greater than the outer radialextent 232 of the saddle portion 230. In some embodiments, the secondouter radial extent 222 may be greater than the outer radial extent 232of the saddle portion 230. In some embodiments, the second outer radialextent 222 may be within about 25% of the first outer radial extent 212.In some embodiments, the second outer radial extent 222 may be withinabout 10% of the first outer radial extent 212. In some embodiments, thesecond outer radial extent 222 may be within about 5% of the first outerradial extent 212. In some embodiments, the second outer radial extent222 may be equal to the first outer radial extent 212. In someembodiments, the outer radial extent 232 of the saddle portion 230 maybe about 10 mm (millimeters) to about 30 mm, about 14 mm to about 25 mm,about 16 mm to about 22 mm, or another suitable range. In someembodiments, the first outer radial extent 212 and/or the second outerradial extent 222 may be about 20 mm to about 40 mm, about 24 mm toabout 35 mm, about 26 mm to about 32 mm, or another suitable range.Other configurations are also contemplated.

In some embodiments, in the deployed configuration, the saddle portion230 may be conically shaped, tapering from the first flange portion 210to the second flange portion 220. For instance, the saddle portion 230of the tubular body 200 may include a first radially inward taper 234extending from the first flange portion 210 toward the second flangeportion 220. In some embodiments, the first radially inward taper 234may extend from the first flange portion 210 to the second flangeportion 220. In some embodiments, the first radially inward taper 234may extend past the second flange portion 220 toward and/or to thesecond end 204. In some embodiments, an outer radial extent of thetubular body 200 and/or the expandable framework at the second end 204may be substantially less than an outer radial extent of the tubularbody 200 and/or the expandable framework at the first end 202. In someembodiments, the outer radial extent of the tubular body 200 and/or theexpandable framework at the second end 204 may be about 25% to about 50%less than the outer radial extent of the tubular body 200 and/or theexpandable framework at the first end 202. Other configurations are alsocontemplated.

In some embodiments, in the deployed configuration, the first flangeportion 210 may comprise multiple spaced apart flanges, such as a firstflange 214 proximate the first end 202 and a second flange 216longitudinally spaced apart from the first flange 214 toward the secondend 204. The first flange 214 and the second flange 216 may be orientedgenerally transverse to a central longitudinal axis of the tubular body200. In some embodiments, the second flange 216 may be longitudinallyspaced apart from the first flange 214 about 2 mm to about 20 mm, about4 mm to about 15 mm, about 5 mm to about 10 mm, or another suitablerange. In some embodiments, the first flange 214 and/or the secondflange 216 may have an axial thickness of about 1 mm to about 7 mm,about 2 mm to about 6 mm, about 3 mm to about 5 mm, or another suitablerange. Other configurations are also contemplated.

In some embodiments, in the deployed configuration, the second flangeportion 220 may comprise multiple spaced apart flanges, such as a thirdflange 224 proximate the second end 204 and a fourth flange 226longitudinally spaced apart from the third flange 224 toward the firstend 202. The third flange 224 and the fourth flange 226 may be orientedgenerally transverse to the central longitudinal axis of the tubularbody 200. In some embodiments, the fourth flange 226 may belongitudinally spaced apart from the third flange 224 about 2 mm toabout 20 mm, about 4 mm to about 15 mm, about 5 mm to about 10 mm, oranother suitable range. In some embodiments, the third flange 224 and/orthe fourth flange 226 may have an axial thickness of about 1 mm to about7 mm, about 2 mm to about 6 mm, about 3 mm to about 5 mm, or anothersuitable range. Other configurations are also contemplated. In at leastsome embodiments, the second flange portion 220, the third flange 224,and/or the fourth flange 226 may extend a greater distance radiallyoutward from the saddle portion 230 than the first flange portion 210,the first flange 214, and/or the second flange 216.

In some embodiments, in the deployed configuration, the first flangeportion 210 (and/or the first flange 214 and the second flange 216) maybe configured to resist collapsing radially inward under a first radialinward force, the second flange portion 220 (and/or the third flange 224and the fourth flange 226) may be configured to resist collapsingradially inward under a second radial inward force, and the saddleportion 230 may be configured to resist collapsing radially inward undera third radial inward force less than the first radial inward force andthe second radial inward force. In some embodiments, the first radialinward force may be within about 25% of the second radial inward force.In some embodiments, the first radial inward force may be within about10% of the second radial inward force. In some embodiments, the firstradial inward force may be within about 5% of the second radial inwardforce. In some embodiments, the third radial inward force may be lessthan about 75% of the first radial inward force and/or the second radialinward force. In some embodiments, the third radial inward force may beless than about 50% of the first radial inward force and/or the secondradial inward force. In some embodiments, the first radial inward forceand/or the second radial inward force may be about 300% to about 500%greater than the third radial inward force. Other configurations arealso contemplated.

In some embodiments, in the deployed configuration, the tubular body 200may define an outer surface that may extend, sequentially, from thefirst end: longitudinally, radially outward, curve back on itself toradially inward, longitudinally, radially outward, curve back on itselfto radially inward, longitudinally along a radially inward taper,radially outward, curve back on itself to radially inward,longitudinally (and in at least some embodiments, longitudinally along aradially inward taper), radially outward, curve back on itself toradially inward, and longitudinally (and in at least some embodiments,longitudinally along a radially inward taper), to the second end. Inother words, each flange may include first and second radially extendingwall portions longitudinally spaced apart from one another with anapical curved region spanning therebetween at the outer extent of theflange, with a first radially extending wall portion extend radiallyoutward from the central longitudinal axis to an outer extent of theflange and the second radially extending wall portion extending radiallyinward from the outer extent of the flange toward the centrallongitudinal axis. Other configurations are also contemplated.

In some embodiments, the tubular body 200 may be formed from a pluralityof filaments or wires that may be woven, braided, wound, knitted, andcombinations thereof, around a central longitudinal axis to form thetubular body 200. The tubular body 200 may include multiple filaments orwires of a metal material, such as nitinol or nitinol-containingmaterial, or other nickel-titanium alloy, for example. In someinstances, the filaments or wires may have a diameter of about 0.011inches (0.2794 mm), for example. The number and the diameters of thefilaments or wires, which may be the same or different, are notlimiting, and other numbers and other diameters of filaments or wiresmay suitably be used. Desirably, an even number of filaments or wiresmay be used, for example, from about 2 to about 50 filaments or wires,about 6 to about 40 filaments or wires, about 10 to about 36 filamentsor wires, etc.

Desirably, the filaments or wires are made from any suitable implantablebiocompatible material, including without limitation nitinol, stainlesssteel, cobalt-based alloy such as Elgiloy®, platinum, gold, titanium,tantalum, niobium, polymeric materials and combinations thereof. Usefuland nonlimiting examples of polymeric stent materials includepoly(L-lactide) (PLLA), poly(D,L-lactide) (PLA), poly(glycolide) (PGA),poly(L-lactide-co-D,L-lactide) (PLLA/PLA), poly(L-lactide-co-glycolide)(PLLA/PGA), poly(D,L-lactide-co-glycolide) (PLA/PGA),poly(glycolide-co-trimethylene carbonate) (PGA/PTMC), polydioxanone(PDS), Polycaprolactone (PCL), polyhydroxybutyrate (PHBT),poly(phosphazene) poly(D,L-lactide-co-caprolactone) PLA/PCL),poly(glycolide-co-caprolactone) (PGA/PCL), poly(phosphate ester) and thelike. Filaments or wires made from polymeric materials may also includeradiopaque materials, such as metallic-based powders, particulates orpastes which may be incorporated into the polymeric material. Forexample, the radiopaque material may be blended with the polymercomposition from which the polymeric filaments or wires are formed, andsubsequently fashioned into the tubular body 200 as described herein.Alternatively, the radiopaque material may be applied to the surface ofthe metal or polymer filaments or wires of the tubular body 200. Ineither embodiment, various radiopaque materials and their salts andderivatives may be used including, without limitation, bismuth, bariumand its salts such as barium sulphate, tantalum, tungsten, gold,platinum and titanium, to name a few. Additional useful radiopaquematerials may be found in U.S. Pat. No. 6,626,936, the contents of whichare incorporated herein by reference. Metallic complexes useful asradiopaque materials are also contemplated. The tubular body 200 may beselectively made radiopaque at desired areas along the filaments orwires or may be fully radiopaque.

In some instances, the filaments or wires may have a compositeconstruction having an inner core of tantalum, gold, platinum, tungsten,iridium or combination thereof and an outer member or layer of nitinolto provide a composite wire for improved radiopacity or visibility. Inone example, the inner core may be platinum and the outer layer may benitinol. The inner core of platinum may represent about at least 10% ofthe filaments or wires based on overall cross-sectional percentage.Moreover, nitinol that has not been treated for shape memory such as byheating, shaping and cooling the nitinol at its martensitic andaustenitic phases, is also useful as the outer layer. Further details ofsuch composite wires may be found in U.S. Pat. No. 7,101,392, thecontents of which is incorporated herein by reference. The filaments orwires may be made from nitinol, or composite filaments or wires having acentral core of platinum and an outer layer of nitinol. Further, thefilling weld material, if required by welding processes such as MIG, mayalso be made from nitinol, stainless steel, cobalt-based alloy such asElgiloy, platinum, gold, titanium, tantalum, niobium, and combinationsthereof. Additional and/or other materials suitable for use in thetubular body 200 are described below.

In some embodiments, the tubular body 200 and/or the expandableframework may optionally include a polymeric cover 240 disposed on atleast a portion of the tubular body 200 and/or the expandable framework.In some embodiments, the polymeric cover 240 may be disposed on thesaddle portion 230, as shown in FIG. 2 for example. In some embodiments,the polymeric cover 240 may additionally or alternatively be disposed onthe first flange portion 210 and/or the second flange portion 220. Insome embodiments, the polymeric cover 240 may be disposed on the firstflange portion 210, the second flange portion 220, and the saddleportion 230. In some embodiments, the polymeric cover 240 may bedisposed on and/or along an outer surface of the tubular body 200 and/orthe expandable framework. In some embodiments, the tubular body 200and/or the expandable framework may be embedded in the polymeric cover240. In some embodiments, the polymeric cover 240 may be disposed onand/or along an inner surface of the tubular body 200 and/or theexpandable framework. In some embodiments, the polymeric cover 240 maybe fixedly or releasably secured to, bonded to, or otherwise attached tothe tubular body 200 and/or the expandable framework. In someembodiments, the polymeric cover 240 may be impermeable to fluids,debris, medical instruments, etc. Some suitable but non-limitingmaterials for the polymeric cover 240 are described below.

FIG. 3 illustrates an example stent (which term may be usedinterchangeably with the term “endoprosthesis”) comprising a tubularbody 300 configured to shift between a delivery configuration (e.g.,FIG. 4 ) and a deployed configuration, the tubular body 300 having afirst end 302 and a second end 304. In some embodiments, the deliveryconfiguration may be axially elongated and/or radially collapsed orcompressed compared to the deployed configuration. The deployedconfiguration may be axially shortened and/or radially expanded comparedto the delivery configuration. The tubular body 300 may be constructedand/or may function similar to the tubular body 100/200 describedherein, except for any specific differences noted.

In some embodiments, the tubular body 300 may comprise an expandableframework. In at least some embodiments, the tubular body 300 and/or theexpandable framework may be self-expandable. For example, the tubularbody 300 and/or the expandable framework may be formed from a shapememory material. In some embodiments, the tubular body 300 and/or theexpandable framework may be mechanically expandable. For example, thetubular body 300 and/or the expandable framework may be expandable usingan inflatable balloon, using an actuation member, or other suitablemeans. During delivery to a treatment site, the tubular body 300 and/orthe expandable framework may be disposed within a lumen of a deliverysheath in the delivery configuration. Upon removal from the lumen of thedelivery sheath, the tubular body 300 and/or the expandable frameworkmay be shifted to the deployed configuration.

In some embodiments, in the deployed configuration, the tubular body 300and/or the expandable framework may define a first flange portion 310proximate the first end 302, a second flange portion 320 proximate thesecond end 304, and a saddle portion 330 extending from the first flangeportion 310 to the second flange portion 320. The tubular body 300and/or the expandable framework may define an overall longitudinallength 308 extending from the first end 302 to the second end 304. Insome embodiments, a longitudinal length 338 of the saddle portion 330may be at least 50% of the overall longitudinal length 308 of thetubular body 300. In some embodiments, the longitudinal length 338 ofthe saddle portion 330 may be at least 75% of the overall longitudinallength 308 of the tubular body 300. The tubular body 300 and/or theexpandable framework may define a longitudinally oriented lumenextending therethrough from the first end 302 to the second end 304. Inat least some embodiments, the first flange portion 310 and/or thesecond flange portion 320 may be coaxial with the saddle portion 330. Inat least some embodiments, the first flange portion 310 and the secondflange portion 320 may be monolithically formed with the saddle portion330 as a single unitary structure. In some embodiments, at least aportion of the tubular body 300 and/or the expandable framework extendsproximal of the first flange portion 310. In some embodiments, at leasta portion of the tubular body 300 and/or the expandable frameworkextends distal of the second flange portion 320.

In some embodiments, in the deployed configuration, the saddle portion330 may have an outer radial extent 332, the first flange portion 310may have a first outer radial extent 312, and the second flange portion320 may have a second outer radial extent 322. In some embodiments, thefirst outer radial extent 312 may be greater than the outer radialextent 332 of the saddle portion 330. In some embodiments, the secondouter radial extent 322 may be greater than the outer radial extent 332of the saddle portion 330. In some embodiments, the second outer radialextent 322 may be within about 25% of the first outer radial extent 312.In some embodiments, the second outer radial extent 322 may be withinabout 10% of the first outer radial extent 312. In some embodiments, thesecond outer radial extent 322 may be within about 5% of the first outerradial extent 312. In some embodiments, the second outer radial extent322 may be equal to the first outer radial extent 312. In someembodiments, the outer radial extent 332 of the saddle portion 330 maybe about 10 mm (millimeters) to about 30 mm, about 14 mm to about 25 mm,about 16 mm to about 22 mm, or another suitable range. In someembodiments, the first outer radial extent 312 and/or the second outerradial extent 322 may be about 20 mm to about 40 mm, about 24 mm toabout 35 mm, about 26 mm to about 32 mm, or another suitable range. Insome embodiments, an outer radial extent of the tubular body 300 and/orthe expandable framework at the first end 302 may be substantially equalto an outer radial extent of the tubular body 300 and/or the expandableframework at the second end 304. Other configurations are alsocontemplated.

In some embodiments, in the deployed configuration, the saddle portion330 may be hourglass shaped, tapering from each of the first flangeportion 310 and the second flange portion 320 to a necked down centralregion. For instance, the saddle portion 330 of the tubular body 300 mayinclude a first radially inward taper 334 extending from the firstflange portion 310 toward the second flange portion 320. In someembodiments, the saddle portion 330 of the tubular body 300 may includea second radially inward taper 336 extending from the second flangeportion 320 toward the first flange portion 310. In some embodiments,the first radially inward taper 334 and the second radially inward taper336 may converge and/or meet at a reduced diameter neck region 333 ofthe saddle portion 330 disposed between the first flange portion 310 andthe second flange portion 320. In some embodiments, the reduced diameterneck region 333 may include a constant diameter section extending alonga portion of the longitudinal length 338 of the saddle portion 330between the first radially inward taper 334 and the second radiallyinward taper 336. In some embodiments, the reduced diameter neck region333 of the saddle portion 330 may be about 25% to about 50% less thanthe outer radial extent 332 of the saddle portion 330 at and/or adjacentto the first flange portion 310 and/or the second flange portion 320.Other configurations are also contemplated.

In some embodiments, in the deployed configuration, the first flangeportion 310 may comprise multiple spaced apart flanges, such as a firstflange 314 proximate the first end 302 and a second flange 316longitudinally spaced apart from the first flange 314 toward the secondend 304. The first flange 314 and the second flange 316 may be orientedgenerally transverse to a central longitudinal axis of the tubular body300. In some embodiments, the second flange 316 may be longitudinallyspaced apart from the first flange 314 about 2 mm to about 20 mm, about4 mm to about 15 mm, about 5 mm to about 10 mm, or another suitablerange. In some embodiments, the first flange 314 and/or the secondflange 316 may have an axial thickness of about 1 mm to about 7 mm,about 2 mm to about 6 mm, about 3 mm to about 5 mm, or another suitablerange. Other configurations are also contemplated.

In some embodiments, in the deployed configuration, the second flangeportion 320 may comprise multiple spaced apart flanges, such as a thirdflange 324 proximate the second end 304 and a fourth flange 326longitudinally spaced apart from the third flange 324 toward the firstend 302. The third flange 324 and the fourth flange 326 may be orientedgenerally transverse to the central longitudinal axis of the tubularbody 300. In some embodiments, the fourth flange 326 may belongitudinally spaced apart from the third flange 324 about 2 mm toabout 20 mm, about 4 mm to about 15 mm, about 5 mm to about 10 mm, oranother suitable range. In some embodiments, the third flange 324 and/orthe fourth flange 326 may have an axial thickness of about 1 mm to about7 mm, about 2 mm to about 6 mm, about 3 mm to about 5 mm, or anothersuitable range. Other configurations are also contemplated.

In some embodiments, in the deployed configuration, the first flangeportion 310 (and/or the first flange 314 and the second flange 316) maybe configured to resist collapsing radially inward under a first radialinward force, the second flange portion 320 (and/or the third flange 324and the fourth flange 326) may be configured to resist collapsingradially inward under a second radial inward force, and the saddleportion 330 may be configured to resist collapsing radially inward undera third radial inward force less than the first radial inward force andthe second radial inward force. In some embodiments, the first radialinward force may be within about 25% of the second radial inward force.In some embodiments, the first radial inward force may be within about10% of the second radial inward force. In some embodiments, the firstradial inward force may be within about 5% of the second radial inwardforce. In some embodiments, the third radial inward force may be lessthan about 75% of the first radial inward force and/or the second radialinward force. In some embodiments, the third radial inward force may beless than about 50% of the first radial inward force and/or the secondradial inward force. In some embodiments, the first radial inward forceand/or the second radial inward force may be about 300% to about 500%greater than the third radial inward force. Other configurations arealso contemplated.

In some embodiments, in the deployed configuration, the tubular body 200may define an outer surface that may extend, sequentially, from thefirst end: longitudinally, radially outward, curve back on itself toradially inward, longitudinally, radially outward, curve back on itselfto radially inward, longitudinally along a radially inward taper,longitudinally along a radially outward taper, radially outward, curveback on itself to radially inward, longitudinally, radially outward,curve back on itself to radially inward, and longitudinally, to thesecond end. In other words, each flange may include first and secondradially extending wall portions longitudinally spaced apart from oneanother with an apical curved region spanning therebetween at the outerextent of the flange, with a first radially extending wall portionextend radially outward from the central longitudinal axis to an outerextent of the flange and the second radially extending wall portionextending radially inward from the outer extent of the flange toward thecentral longitudinal axis. Other configurations are also contemplated.

In some embodiments, the tubular body 300 may be formed from a pluralityof filaments or wires that may be woven, braided, wound, knitted, andcombinations thereof, around a central longitudinal axis to form thetubular body 300. The tubular body 300 may include multiple filaments orwires of a metal material, such as nitinol or nitinol-containingmaterial, or other nickel-titanium alloy, for example. In someinstances, the filaments or wires may have a diameter of about 0.011inches (0.2794 mm), for example. The number and the diameters of thefilaments or wires, which may be the same or different, are notlimiting, and other numbers and other diameters of filaments or wiresmay suitably be used. Desirably, an even number of filaments or wiresmay be used, for example, from about 2 to about 50 filaments or wires,about 6 to about 40 filaments or wires, about 10 to about 36 filamentsor wires, etc.

Desirably, the filaments or wires are made from any suitable implantablebiocompatible material, including without limitation nitinol, stainlesssteel, cobalt-based alloy such as Elgiloy®, platinum, gold, titanium,tantalum, niobium, polymeric materials and combinations thereof. Usefuland nonlimiting examples of polymeric stent materials includepoly(L-lactide) (PLLA), poly(D,L-lactide) (PLA), poly(glycolide) (PGA),poly(L-lactide-co-D,L-lactide) (PLLA/PLA), poly(L-lactide-co-glycolide)(PLLA/PGA), poly(D,L-lactide-co-glycolide) (PLA/PGA),poly(glycolide-co-trimethylene carbonate) (PGA/PTMC), polydioxanone(PDS), Polycaprolactone (PCL), polyhydroxybutyrate (PHBT),poly(phosphazene) poly(D,L-lactide-co-caprolactone) PLA/PCL),poly(glycolide-co-caprolactone) (PGA/PCL), poly(phosphate ester) and thelike. Filaments or wires made from polymeric materials may also includeradiopaque materials, such as metallic-based powders, particulates orpastes which may be incorporated into the polymeric material. Forexample, the radiopaque material may be blended with the polymercomposition from which the polymeric filaments or wires are formed, andsubsequently fashioned into the tubular body 300 as described herein.Alternatively, the radiopaque material may be applied to the surface ofthe metal or polymer filaments or wires of the tubular body 300. Ineither embodiment, various radiopaque materials and their salts andderivatives may be used including, without limitation, bismuth, bariumand its salts such as barium sulphate, tantalum, tungsten, gold,platinum and titanium, to name a few. Additional useful radiopaquematerials may be found in U.S. Pat. No. 6,626,936, the contents of whichare incorporated herein by reference. Metallic complexes useful asradiopaque materials are also contemplated. The tubular body 300 may beselectively made radiopaque at desired areas along the filaments orwires or may be fully radiopaque.

In some instances, the filaments or wires may have a compositeconstruction having an inner core of tantalum, gold, platinum, tungsten,iridium or combination thereof and an outer member or layer of nitinolto provide a composite wire for improved radiopacity or visibility. Inone example, the inner core may be platinum and the outer layer may benitinol. The inner core of platinum may represent about at least 10% ofthe filaments or wires based on overall cross-sectional percentage.Moreover, nitinol that has not been treated for shape memory such as byheating, shaping and cooling the nitinol at its martensitic andaustenitic phases, is also useful as the outer layer. Further details ofsuch composite wires may be found in U.S. Pat. No. 7,101,392, thecontents of which is incorporated herein by reference. The filaments orwires may be made from nitinol, or composite filaments or wires having acentral core of platinum and an outer layer of nitinol. Further, thefilling weld material, if required by welding processes such as MIG, mayalso be made from nitinol, stainless steel, cobalt-based alloy such asElgiloy, platinum, gold, titanium, tantalum, niobium, and combinationsthereof. Additional and/or other materials suitable for use in thetubular body 300 are described below.

In some embodiments, the tubular body 300 and/or the expandableframework may optionally include a polymeric cover 340 disposed on atleast a portion of the tubular body 300 and/or the expandable framework.In some embodiments, the polymeric cover 340 may be disposed on thesaddle portion 330, as shown in FIG. 3 for example. In some embodiments,the polymeric cover 340 may additionally or alternatively be disposed onthe first flange portion 310 and/or the second flange portion 320. Insome embodiments, the polymeric cover 340 may be disposed on the firstflange portion 310, the second flange portion 320, and the saddleportion 330. In some embodiments, the polymeric cover 340 may bedisposed on and/or along an outer surface of the tubular body 300 and/orthe expandable framework. In some embodiments, the tubular body 300and/or the expandable framework may be embedded in the polymeric cover340. In some embodiments, the polymeric cover 340 may be disposed onand/or along an inner surface of the tubular body 300 and/or theexpandable framework. In some embodiments, the polymeric cover 340 maybe fixedly or releasably secured to, bonded to, or otherwise attached tothe tubular body 300 and/or the expandable framework. In someembodiments, the polymeric cover 340 may be impermeable to fluids,debris, medical instruments, etc. Some suitable but non-limitingmaterials for the polymeric cover 340 are described below.

FIGS. 4 and 5 illustrate aspects of a method of treating a stricture 12in a body lumen 10. The method is described herein with respect to thetubular body 100. However, the skilled artisan will recognize that thesame method and/or steps may apply equally to the tubular body 200and/or the tubular body 300, which elements may be used and/or appliedinterchangeably within the description provided.

In some embodiments, the method may include loading and/or positioning astent including the tubular body 100 within a delivery catheter 50 in adelivery configuration. The delivery configuration may be and/or includean elongated and/or radially compressed configuration of the tubularbody 100.

In some embodiments, the method may include positioning the stent withinthe body lumen 10 in the delivery configuration using the deliverycatheter 50, wherein the stent is positioned with the saddle portion 130of the stent spanning the stricture 12, the first flange portion 110proximal of the stricture 12, and the second flange portion 120 distalof the stricture 12, as seen in FIG. 4 for example. The method mayfurther include retracting and/or withdrawing the delivery catheter 50from the stricture 12 and/or the body lumen 10 to release the stentand/or the tubular body 100 in the delivery configuration at thestricture 12.

In some embodiments, the method may include shifting the stent and/orthe tubular body 100 from the delivery configuration to the deployedconfiguration. The deployed configuration may be and/or include alongitudinally shortened and/or radially expanded configuration of thetubular body 100. In some embodiments, in the deployed configuration,the first flange portion 110 may have a first radial outer extentgreater than an outer radial extent of the saddle portion 130. In someembodiments, in the deployed configuration, the second flange portion120 may have a second radial outer extent greater than an outer radialextent of the saddle portion 130. In at least some embodiments, in thedeployed configuration, the saddle portion 130 may span an entirelongitudinal length of the stricture 12.

As may be seen in FIG. 5 for example, in some embodiments, in thedeployed configuration, a first flange 114 of the first flange portion110 and a second flange 116 of the first flange portion 110longitudinally spaced apart from the first flange 114 may capture afirst portion 22 of a wall 20 of the body lumen 10 therebetween toanchor the stent and/or the tubular body 100 adjacent the stricture 12.In some embodiments, the first portion 22 of the wall 20 of the bodylumen 10 may form a substantially annular structure extending radiallyinward from the wall 20 when captured between the first flange 114 andthe second flange 116. In some embodiments, the wall 20 may be deflectedradially outward by the first flange 114 and/or the second flange 116 inthe deployed configuration.

In addition or alternatively, in some embodiments, in the deployedconfiguration, a third flange 124 of the second flange portion 120 and afourth flange 126 of the second flange portion 120 longitudinally spacedapart from the third flange 124 may capture a second portion 24 of thewall 20 of the body lumen 10 therebetween to anchor the stent and/or thetubular body 100 adjacent the stricture 12. In some embodiments, thesecond portion 24 of the wall 20 of the body lumen 10 may form asubstantially annular structure extending radially inward from the wall20 when captured between the third flange 124 and the fourth flange 126.In some embodiments, the wall 20 may be deflected radially outward bythe third flange 124 and the fourth flange 126 in the deployedconfiguration.

The materials that can be used for the various components of the stent100/200/300 and the various elements thereof disclosed herein mayinclude those commonly associated with medical devices. For simplicitypurposes, the following discussion makes reference to the stent100/200/300. However, this is not intended to limit the devices andmethods described herein, as the discussion may be applied to otherelements, members, components, or devices disclosed herein, such as, butnot limited to, the expandable framework, the first flange portion, thesecond flange portion, the saddle portion, the polymeric cover, and/orelements or components thereof.

In some embodiments, the stent 100/200/300, and/or components thereof,may be made from a metal, metal alloy, polymer (some examples of whichare disclosed below), a metal-polymer composite, ceramics, combinationsthereof, and the like, or other suitable material.

Some examples of suitable polymers may include polytetrafluoroethylene(PTFE), ethylene tetrafluoroethylene (ETFE), fluorinated ethylenepropylene (FEP), polyoxymethylene (POM, for example, DELRIN® availablefrom DuPont), polyether block ester, polyurethane (for example,Polyurethane 85A), polypropylene (PP), polyvinylchloride (PVC),polyether-ester (for example, ARNITEL® available from DSM EngineeringPlastics), ether or ester based copolymers (for example,butylene/poly(alkylene ether) phthalate and/or other polyesterelastomers such as HYTREL® available from DuPont), polyamide (forexample, DURETHAN® available from Bayer or CRISTAMID® available from ElfAtochem), elastomeric polyamides, block polyamide/ethers, polyetherblock amide (PEBA, for example available under the trade name PEBAX®),ethylene vinyl acetate copolymers (EVA), silicones, polyethylene (PE),Marlex high-density polyethylene, Marlex low-density polyethylene,linear low density polyethylene (for example REXELL®), polyester,polybutylene terephthalate (PBT), polyethylene terephthalate (PET),polytrimethylene terephthalate, polyethylene naphthalate (PEN),polyetheretherketone (PEEK), polyimide (PI), polyetherimide (PEI),polyphenylene sulfide (PPS), polyphenylene oxide (PPO), polyparaphenylene terephthalamide (for example, KEVLAR®), polysulfone,nylon, nylon-12 (such as GRILAMID® available from EMS American Grilon),perfluoro(propyl vinyl ether) (PFA), ethylene vinyl alcohol, polyolefin,polystyrene, epoxy, polyvinylidene chloride (PVdC),poly(styrene-b-isobutylene-b-styrene) (for example, SIBS and/or SIBS50A), polycarbonates, polyurethane silicone copolymers (for example,ElastEon® from Aortech Biomaterials or ChronoSil® from AdvanSourceBiomaterials), biocompatible polymers, other suitable materials, ormixtures, combinations, copolymers thereof, polymer/metal composites,and the like. In some embodiments the sheath can be blended with aliquid crystal polymer (LCP). For example, the mixture can contain up toabout 6 percent LCP.

Some examples of suitable metals and metal alloys include stainlesssteel, such as 304V, 304L, and 316LV stainless steel; mild steel;nickel-titanium alloy such as linear-elastic and/or super-elasticnitinol; other nickel alloys such as nickel-chromium-molybdenum alloys(e.g., UNS: N06625 such as INCONEL® 625, UNS: N06022 such as HASTELLOY®C-22®, UNS: N10276 such as HASTELLOY® C276®, other HASTELLOY® alloys,and the like), nickel-copper alloys (e.g., UNS: N04400 such as MONEL®400, NICKELVAC® 400, NICORROS® 400, and the like),nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R30035 such asMP35-N® and the like), nickel-molybdenum alloys (e.g., UNS: N10665 suchas HASTELLOY® ALLOY B2®), other nickel-chromium alloys, othernickel-molybdenum alloys, other nickel-cobalt alloys, other nickel-ironalloys, other nickel-copper alloys, other nickel-tungsten or tungstenalloys, and the like; cobalt-chromium alloys; cobalt-chromium-molybdenumalloys (e.g., UNS: R30003 such as ELGILOY®, PHYNOX®, and the like);platinum enriched stainless steel; titanium; platinum; palladium; gold;combinations thereof; or any other suitable material.

In some embodiments, a linear elastic and/or non-super-elasticnickel-titanium alloy may be in the range of about 50 to about 60 weightpercent nickel, with the remainder being essentially titanium. In someembodiments, the composition is in the range of about 54 to about 57weight percent nickel. One example of a suitable nickel-titanium alloyis FHP-NT alloy commercially available from Furukawa Techno Material Co.of Kanagawa, Japan. Other suitable materials may include ULTANIUM™(available from Neo-Metrics) and GUM METAL™ (available from Toyota). Insome other embodiments, a superelastic alloy, for example a superelasticnitinol can be used to achieve desired properties.

In at least some embodiments, portions or all of the stent 100/200/300,and/or components thereof, may also be doped with, made of, or otherwiseinclude a radiopaque material. Radiopaque materials are understood to bematerials capable of producing a relatively bright image on afluoroscopy screen or another imaging technique during a medicalprocedure. This relatively bright image aids the user of the stent100/200/300 in determining its location. Some examples of radiopaquematerials can include, but are not limited to, gold, platinum,palladium, tantalum, tungsten alloy, polymer material loaded with aradiopaque filler, and the like. Additionally, other radiopaque markerbands and/or coils may also be incorporated into the design of the stent100/200/300 to achieve the same result.

In some embodiments, a degree of Magnetic Resonance Imaging (MM)compatibility is imparted into the stent 100/200/300 and/or otherelements disclosed herein. For example, the stent 100/200/300, and/orcomponents or portions thereof, may be made of a material that does notsubstantially distort the image and create substantial artifacts (i.e.,gaps in the image). Certain ferromagnetic materials, for example, maynot be suitable because they may create artifacts in an MRI image. Thestent 100/200/300, or portions thereof, may also be made from a materialthat the MRI machine can image. Some materials that exhibit thesecharacteristics include, for example, tungsten,cobalt-chromium-molybdenum alloys (e.g., UNS: R30003 such as ELGILOY®,PHYNOX®, and the like), nickel-cobalt-chromium-molybdenum alloys (e.g.,UNS: R30035 such as MP35-N® and the like), nitinol, and the like, andothers.

In some embodiments, the stent 100/200/300 and/or other elementsdisclosed herein may include a fabric material disposed over or withinthe structure. The fabric material may be composed of a biocompatiblematerial, such a polymeric material or biomaterial, adapted to promotetissue ingrowth. In some embodiments, the fabric material may include abioabsorbable material. Some examples of suitable fabric materialsinclude, but are not limited to, polyethylene glycol (PEG), nylon,polytetrafluoroethylene (PTFE, ePTFE), a polyolefinic material such as apolyethylene, a polypropylene, polyester, polyurethane, and/or blends orcombinations thereof.

In some embodiments, the stent 100/200/300 and/or other elementsdisclosed herein may include and/or be formed from a textile material.Some examples of suitable textile materials may include synthetic yarnsthat may be flat, shaped, twisted, textured, pre-shrunk or un-shrunk.Synthetic biocompatible yarns suitable for use in the present inventioninclude, but are not limited to, polyesters, including polyethyleneterephthalate (PET) polyesters, polypropylenes, polyethylenes,polyurethanes, polyolefins, polyvinyls, polymethylacetates, polyamides,naphthalene dicarboxylene derivatives, natural silk, andpolytetrafluoroethylenes. Moreover, at least one of the synthetic yarnsmay be a metallic yarn or a glass or ceramic yarn or fiber. Usefulmetallic yarns include those yarns made from or containing stainlesssteel, platinum, gold, titanium, tantalum or a Ni—Co—Cr-based alloy. Theyarns may further include carbon, glass or ceramic fibers. Desirably,the yarns are made from thermoplastic materials including, but notlimited to, polyesters, polypropylenes, polyethylenes, polyurethanes,polynaphthalenes, polytetrafluoroethylenes, and the like. The yarns maybe of the multifilament, monofilament, or spun types. The type anddenier of the yarn chosen may be selected in a manner which forms abiocompatible and implantable prosthesis and, more particularly, avascular structure having desirable properties.

In some embodiments, the stent 100/200/300 and/or other elementsdisclosed herein may include and/or be treated with a suitabletherapeutic agent. Some examples of suitable therapeutic agents mayinclude anti-thrombogenic agents (such as heparin, heparin derivatives,urokinase, and PPack (dextrophenylalanine proline argininechloromethylketone)); anti-proliferative agents (such as enoxaparin,angiopeptin, monoclonal antibodies capable of blocking smooth musclecell proliferation, hirudin, and acetylsalicylic acid);anti-inflammatory agents (such as dexamethasone, prednisolone,corticosterone, budesonide, estrogen, sulfasalazine, and mesalamine);antineoplastic/antiproliferative/anti-mitotic agents (such aspaclitaxel, 5-fluorouracil, cisplatin, vinblastine, vincristine,epothilones, endostatin, angiostatin and thymidine kinase inhibitors);anesthetic agents (such as lidocaine, bupivacaine, and ropivacaine);anti-coagulants (such as D-Phe-Pro-Arg chloromethyl keton, an RGDpeptide-containing compound, heparin, anti-thrombin compounds, plateletreceptor antagonists, anti-thrombin antibodies, anti-platelet receptorantibodies, aspirin, prostaglandin inhibitors, platelet inhibitors, andtick antiplatelet peptides); vascular cell growth promoters (such asgrowth factor inhibitors, growth factor receptor antagonists,transcriptional activators, and translational promoters); vascular cellgrowth inhibitors (such as growth factor inhibitors, growth factorreceptor antagonists, transcriptional repressors, translationalrepressors, replication inhibitors, inhibitory antibodies, antibodiesdirected against growth factors, bifunctional molecules consisting of agrowth factor and a cytotoxin, bifunctional molecules consisting of anantibody and a cytotoxin); cholesterol-lowering agents; vasodilatingagents; and agents which interfere with endogenous vasoactivemechanisms.

It should be understood that this disclosure is, in many respects, onlyillustrative. Changes may be made in details, particularly in matters ofshape, size, and arrangement of steps without exceeding the scope of theinvention. This may include, to the extent that it is appropriate, theuse of any of the features of one example embodiment being used in otherembodiments. The invention's scope is, of course, defined in thelanguage in which the appended claims are expressed.

What is claimed is:
 1. A stent configured to span a stricture in a bodylumen, comprising: a tubular body configured to shift between a deliveryconfiguration and a deployed configuration, the tubular body having afirst end and a second end; wherein in the deployed configuration: thetubular body defines a first flange portion proximate the first end, asecond flange portion proximate the second end, and a saddle portionextending from the first flange portion to the second flange portion,wherein the first flange portion includes a first flange proximate thefirst end and a second flange longitudinally spaced apart about 5 mm toabout 10 mm from the first flange toward the second end, wherein thesecond flange portion includes a third flange proximate the second endand a fourth flange longitudinally spaced apart about 5 mm to about 10mm from the third flange toward the first end; the tubular body furtherdefining an overall longitudinal length extending from the first end tothe second end; the saddle portion has an outer radial extent, the firstflange portion has a first outer radial extent, and the second flangeportion has a second outer radial extent; the first outer radial extentis greater than the outer radial extent of the saddle portion; thesecond outer radial extent is greater than the outer radial extent ofthe saddle portion; a longitudinal length of the saddle portion is atleast 50% of the overall longitudinal length of the tubular body; andwherein in the deployed configuration, the first and second flanges areconfigured to resist a first radial inward force, the third and fourthflanges are configured to resist a second radial inward force, and thesaddle portion is configured to resist a third radial inward force lessthan the first radial inward force and the second radial inward force.2. The stent of claim 1, wherein in the deployed configuration, thefirst and second flanges are configured to resist the first radialinward force that is within 10% of the second radial inward force. 3.The stent of claim 1, wherein in the deployed configuration, the saddleportion is configured to resist the third radial inward force that isless than 75% of the first radial inward force or the second radialinward force.
 4. The stent of claim 1, wherein in the deployedconfiguration, the longitudinal length of the saddle portion is at least75% of the overall length of the tubular body.
 5. The stent of claim 1,wherein at least a portion of the tubular body includes a cover member.6. An esophageal stent configured to span a stricture in an esophagus,comprising: a tubular body configured to shift between a deliveryconfiguration and a deployed configuration, the tubular body having afirst end and a second end; wherein in the deployed configuration: thetubular body defines a first flange portion proximate the first end, asecond flange portion proximate the second end, and a saddle portionextending from the first flange portion to the second flange portion;the tubular body further defining an overall longitudinal lengthextending from the first end to the second end; the saddle portion hasan outer radial extent, the first flange portion has a first outerradial extent, and the second flange portion has a second outer radialextent; the first outer radial extent is greater than the outer radialextent of the saddle portion; the second outer radial extent is greaterthan the outer radial extent of the saddle portion; wherein in thedeployed configuration, the first flange portion comprises a firstflange proximate the first end and a second flange longitudinally spacedapart about 5 mm to about 10 mm from the first flange toward the secondend; wherein in the deployed configuration, the second flange portioncomprises a third flange proximate the second end and a fourth flangelongitudinally spaced apart about 5 mm to about 10 mm from the thirdflange toward the first end; and wherein in the deployed configuration,the first and second flanges are configured to resist a first radialinward force, the third and fourth flanges are configured to resist asecond radial inward force, and the saddle portion is configured toresist a third radial inward force less than the first radial inwardforce and the second radial inward force.
 7. The esophageal stent ofclaim 6, wherein in the deployed configuration, the second outer radialextent is within 10% of the first outer radial extent.
 8. The esophagealstent of claim 6, wherein in the deployed configuration, the secondouter radial extent is within 5% of the first outer radial extent. 9.The esophageal stent of claim 6, wherein at least a portion of thetubular body includes a cover member.
 10. A method of treating astricture in a body lumen, comprising: positioning a stent within thebody lumen in a delivery configuration, wherein the stent is positionedwith a saddle portion of the stent spanning the stricture, a firstflange portion proximal of the stricture, and a second flange portiondistal of the stricture; shifting the stent from the deliveryconfiguration to a deployed configuration, wherein in the deployedconfiguration: the first flange portion has a first outer radial extentgreater than an outer radial extent of the saddle portion; the secondflange portion has a second outer radial extent greater than the outerradial extent of the saddle portion; a first flange of the first flangeportion and a second flange of the first flange portion longitudinallyspaced apart from the first flange by about 5 mm to about 10 mm tocapture a first portion of a wall of the body lumen therebetween toanchor the stent adjacent the stricture; and a third flange of thesecond flange portion and a fourth flange of the second flange portionlongitudinally spaced apart from the third flange by about 5 mm to about10 mm to capture a second portion of the wall of the body lumentherebetween to anchor the stent adjacent the stricture; wherein in thedeployed configuration, the first and second flanges are configured toresist a first radial inward force, the third and fourth flanges areconfigured to resist a second radial inward force, and the saddleportion is configured to resist a third radial inward force less thanthe first radial inward force and the second radial inward force.